Air handling unit and fan therefor

ABSTRACT

The present disclosure provides a fan including a hub and multiple fan blades coupled to the hub and located circumferentially along the hub. Each fan blade extends between a root and a tip edge thereof and includes a first portion inclined at a first predefined angle with respect to the hub. The first portion induces an axial flow of air. The fan blade also includes a second portion extending from the first portion and between a leading edge and a trailing edge of the fan blade. The second portion is embodied as an airfoil defining an angle of attack to induce a radial inward flow of air. A radius of curvature of a trailing edge segment of the second portion is less than a radius of curvature of a leading edge segment of the second portion.

TECHNICAL FIELD

The present disclosure relates, in general, to an air handling unit and, more specifically relates, to a fan of the air handling unit.

BACKGROUND

An air conditioner is referred to as a split type air conditioner when an indoor unit and an outdoor unit thereof are located distant from one another. The outdoor unit in the split type air conditioner typically includes an axial fan as the air mover. The axial fan is located at a top portion of the cabinet and is received coaxially in a venturi. Generally, based on a layout of refrigerant tubes routed along a periphery of the outdoor unit, space available between an outer surface of the venturi and the refrigerant tubes routed through an upper portion of the outdoor unit, may be negligible. Such disposition of the axial fan and the venturi creates a narrow region for flow of air therebetween, thereby causing development of non-uniform pressure differential along a height of the outdoor unit and across refrigerant tubes guided along periphery of the outdoor unit. Since air tends to flow along a path of least resistance, such disposition of the venturi and the fan results in negligible flow of air across the refrigerant tubes located in the narrow region at the upper portion of the outdoor unit, thereby affecting heat exchange between the refrigerant tubes and air flowing therethrough.

In cases where the outdoor unit includes multiple circuits of refrigerant tubes, such disposition of the venturi and the fan may cause few circuits to be devoid of air, thereby developing an instance of airflow maldistribution along the height of the outdoor unit. Such instances of airflow maldistribution may be detrimental to an overall performance of the split type air conditioner.

SUMMARY

According to one aspect of the present disclosure, a fan is disclosed. The fan includes a hub configured to rotate about an axis, and a plurality of fan blades coupled to the hub and located circumferentially along the hub. Each fan blade extends between a root and a tip edge thereof. The fan blade includes a first portion inclined at a first predefined angle with respect to the hub. The first portion is configured to induce an axial flow of air. In an embodiment, the first portion of the fan blade in non-planar. The fan blade further includes a second portion extending from the first portion and between a leading edge and a trailing edge of the fan blade. The second portion is configured as an airfoil defining an angle of attack to induce a radial inward flow of air. In some embodiments, each of the plurality of fan blades is made of one of plastic, metal, and composite material. A radius of curvature of a trailing edge segment of the second portion is less than a radius of curvature of a leading edge segment of the second portion. In an embodiment, a span of the second portion is less than a span of the first portion of the fan blade.

In some embodiments, the induced radial inward flow of air is in a range of about 5% to about 10% of the induced axial flow of air.

In an embodiment, the leading edge segment of the second portion is bent inward towards the hub to define the angle of attack of the fan blade. In an embodiment, a distance between the trailing edge segment of the second portion and a center of the hub is less than a distance between the leading edge segment of the second portion and the center of the hub. In some embodiments, the angle of attack at the tip edge of the fan blade is lower than the angle of attack at a base of the second portion, with respect to a radial direction of the fan blade.

In some embodiments, the angle of attack of the fan blade is in a range of about 3 degrees to about 15 degrees.

In an embodiment, a portion of the leading edge segment of the second portion extends perpendicular with respect to the first portion of the fan blade.

In an embodiment, each of the plurality of fan blades is a swept blade.

According to another aspect of the present disclosure, an air handling unit is disclosed. The air handling unit includes a cabinet, a motor housed within the cabinet, and a fan operably coupled to the motor. The fan is configured to allow a uniform inflow of air at an upper portion of the cabinet and direct the air from inside of the cabinet to outside of the cabinet. The fan includes a hub coupled to a shaft of the motor and configured to rotate about an axis. The fan also includes a plurality of fan blades coupled to the hub and located circumferentially along the hub. Each fan blade extends between a root and a tip edge thereof and includes a first portion inclined at a first predefined angle with respect to the hub. The first portion is configured to induce an axial flow of air. The fan blade also includes a second portion extending from the first portion and between a leading edge and a trailing edge of the fan blade. The second portion is configured as an airfoil defining an angle of attack to induce a radial inward flow of air. A radius of curvature of a trailing edge segment of the second portion is less than a radius of curvature of a leading edge segment of the second portion. In an embodiment, a portion of the leading edge segment of the second portion of the fan blade extends perpendicular with respect to the first portion of the fan blade.

In an embodiment, the leading edge segment of the second portion of the fan blade is bent inward towards the hub to define the angle of attack of the fan blade.

In an embodiment, the air handling unit includes a plurality of refrigerant tubes extending along a periphery of the cabinet. In such arrangement, the fan is configured to induce airflow over the plurality of refrigerant tubes to achieve heat exchange with respect to the plurality of refrigerant tubes.

According to yet another aspect of the present disclosure, an air handling unit is disclosed. The air handling unit includes a cabinet, a motor housed within the cabinet, and a bell mouth extending from the cabinet in a direction inward along a longitudinal axis of the cabinet. The bell mouth is configured to partially conceal the motor in a transverse direction of the cabinet. The air handling unit also includes a fan operably coupled to the motor. The fan is configured to allow a uniform inflow of air at an upper portion of the cabinet and direct the air from inside of the cabinet to outside of the cabinet through the bell mouth. The fan includes a hub coupled to a shaft of the motor and configured to rotate about the longitudinal axis of the cabinet. The fan also includes a plurality of fan blades coupled to the hub and located circumferentially along the hub. Each fan blade extends between a root and a tip edge. The fan blade includes a first portion inclined at a first predefined angle with respect to the hub. The first portion is configured to induce an axial flow of air. The fan blade also includes a second portion extending from the first portion and between a leading edge and a trailing edge of the fan blade. The second portion is configured as an airfoil defining an angle of attack to induce a radial inward flow of air. The second portion is partially concealed by the bell mouth in the transverse direction of the cabinet. A radius of curvature of a trailing edge segment of the second portion is less than a radius of curvature of a leading edge segment of the second portion.

In an embodiment, the induced radial inward flow of air is in a range of about 5% to about 10% of the induced axial flow of air.

In an embodiment, the air handling unit further includes a plurality of refrigerant tubes extending along a periphery of the cabinet. In such arrangement, the fan is configured to induce airflow over the plurality of refrigerant tubes to achieve heat exchange with respect to the plurality of refrigerant tubes.

In an embodiment, the air handling unit further includes a fan guard coupled to an outlet of the bell mouth.

These and other aspects and features of non-limiting embodiments of the present disclosure will become apparent to those skilled in the art upon review of the following description of specific non-limiting embodiments of the disclosure in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of embodiments of the present disclosure (including alternatives and/or variations thereof) may be obtained with reference to the detailed description of the embodiments along with the following drawings, in which:

FIG. 1 is a schematic diagram of a split type air conditioning system;

FIG. 2 is a cross-sectional view of an air handling unit of the split type air conditioning system;

FIG. 3 is a perspective of the cross-sectional view of the air handling unit, according to an embodiment of the present disclosure;

FIG. 4A is a perspective view of a fan of the air handling unit, according to an embodiment of the present disclosure;

FIG. 4B is a front view of a fan blade of the fan of FIG. 4A, according to an embodiment of the present disclosure;

FIG. 4C is a perspective view of the fan blade, according to an embodiment of the present disclosure;

FIG. 5A a front view of the fan blade, according to another embodiment of the present disclosure;

FIG. 5B is a perspective view of the fan blade, according to another embodiment of the present disclosure;

FIG. 6 shows a velocity profile of air flowing across the air handling unit, according to an aspect of the present disclosure;

FIG. 7A is a top view of a fan, according to another embodiment of the present disclosure; and

FIG. 7B is perspective view of a swept blade of the fan of FIG. 7A, according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to specific embodiments or features, examples of which are illustrated in the accompanying drawings. Wherever possible, corresponding or similar reference numbers will be used throughout the drawings to refer to the same or corresponding parts. Moreover, references to various elements described herein, are made collectively or individually when there may be more than one element of the same type. However, such references are merely exemplary in nature. It may be noted that any reference to elements in the singular may also be construed to relate to the plural and vice-versa without limiting the scope of the disclosure to the exact number or type of such elements unless set forth explicitly in the appended claims.

As used herein, the terms “a”, “an” and the like generally carry a meaning of “one or more,” unless stated otherwise. Further, the terms “approximately”, “approximate”, “about”, and similar terms generally refer to ranges that include the identified value within a margin of 20%, 10%, or preferably 5%, and any values therebetween.

Aspects of the present disclosure are directed to a fan and an air handling unit implementing the fan. Specifically, the present disclosure provides constructional improvements to a fan blade of the fan to create air flow in a radial inward direction with respect to a hub of the fan in order to achieve uniform flow of air, for example inlet velocity of the air, in an upper portion of the air handling unit. Such uniform flow of the air aids reduction of airflow maldistribution in the air handling unit, such as an outdoor unit of a split type air conditioning system.

Referring to FIG. 1, a schematic diagram of a split type air conditioning system 100 (hereinafter referred to as “the AC system 100”) is illustrated. The AC system 100 may be selectively operated between an air conditioning mode and a heat pump mode, for cooling and heating, respectively, a predetermined indoor space 102, such as a living room. Broadly, the AC system 100 includes an indoor unit 104 and an outdoor unit 106, and utilizes a predetermined amount of working fluid, such as a refrigerant, for carrying-out heat exchange in the AC system 100. In addition to other components of the AC system 100, the indoor unit 104 and the outdoor unit 106 may be connected through a plurality of connecting pipes, collectively illustrated as, for example, a connecting pipe 108. The indoor unit 104 is located in the predetermined indoor space 102 and the outdoor unit 106 may be positioned in an outdoor environment, such as outside a premises.

Although not particularly illustrated, it will be understood that the indoor unit 104 includes an indoor heat exchanger supported within an indoor unit housing 110. Further, the indoor unit housing 110 may include an indoor air inlet, an indoor air outlet, an indoor refrigerant inlet, and an indoor refrigerant outlet.

FIG. 2 illustrates a cross-sectional view of the outdoor unit 106 and is described with reference to FIG. 1. In an embodiment, besides other components, the outdoor unit 106 includes a cabinet 202, a compressor 204 housed within the cabinet 202, a motor 206 housed within the cabinet 202, a fan 208 disposed within the cabinet 202 and operably coupled to the motor 206, a fan guard 210 disposed along a periphery of the cabinet 202 corresponding to a position of the fan 208, a plurality of refrigerant tubes 212 extending along the periphery of the cabinet, an outdoor refrigerant inlet (not shown) and an outdoor refrigerant outlet (not shown) connected to the plurality of refrigerant tubes 212. The outdoor refrigerant inlet is in fluid communication with the indoor refrigerant outlet and the outdoor refrigerant outlet is in fluid communication with the indoor refrigerant inlet.

Further, the cabinet 202 defines a plurality of openings 214 configured to allow inflow of ambient air “A” into the cabinet 202 from the environment. In such arrangement, the fan 208 is configured to induce airflow over the refrigerant tubes 212 to achieve heat exchange with respect to the refrigerant tubes 212. As such, in a cooling mode operation, the refrigerant flowing through the refrigerant tubes 212 loses heat to the ambient air “A” flowing across the refrigerant tubes 212. In a heating mode operation, the refrigerant flowing through the refrigerant tubes 212 absorbs heat from the ambient air “A” flowing across the refrigerant tubes 212. The fan 208 is configured to direct the air from within the cabinet 202 to the outside of the cabinet 202. As such, the inflow and outflow of air with respect to the cabinet 202 establishes a heat exchange relationship with the refrigerant tubes 212 of the outdoor unit 106. Since the outdoor unit 106 handles the flow of air into and out of the cabinet 202, the outdoor unit 106 is also referred to as “the air handling unit 106” in the present disclosure. In a cooling mode air conditioning operation, the refrigerant flowing through the refrigerant tubes 212 in the outdoor unit 106 loses heat to the air flowing across the refrigerant tubes 212 and is further guided to the indoor unit 104 to absorb heat from the predetermined indoor space 102. The refrigerant is then guided back to the outdoor unit 106 to complete an air conditioning cycle. In a heating mode air conditioning operation, the refrigerant flowing through the refrigerant tubes 212 in the outdoor unit 106 absorbs heat from the air flowing across the refrigerant tubes 212 and is further guided to the indoor unit 104 to dissipate heat to the predetermined indoor space 102.

FIG. 3 shows a perspective view of the cross-section of the cabinet 202 of FIG. 2. In an embodiment, the air handling unit 106 includes a bell mouth 302 that extends from the cabinet 202 in a direction inward along a longitudinal axis “L” of the cabinet 202. In such embodiments, the fan guard 210 may be coupled to an outlet of the bell mouth 302. In some implementations, the bell mouth 302 may be embodied as a flange extending either substantially perpendicular to a peripheral edge of the cabinet 202 or extending inclined with respect to the peripheral edge of the cabinet 202. The bell mouth 302 is configured to partially conceal the motor 206 in a transverse direction (indicated by an arrow “T” in FIG. 2 and FIG. 3) of the cabinet 202. As used herein, the term “transverse direction” may refer to a direction that is perpendicular to the longitudinal axis “L” of the cabinet 202. In one embodiment, the bell mouth 302 may be integral to the cabinet 202. In another embodiment, the bell mouth 302 may be an external component configured to couple to the peripheral edge of the cabinet 302, such that the bell mouth 302 is aligned with the fan guard 210. In such arrangement, the fan 208 is configured to allow a uniform inflow of air at an upper portion 304 of the cabinet 202 and direct the air from inside of the cabinet 202 to the outside of the cabinet 202 through the bell mouth 302.

FIG. 4A illustrates a perspective view of the fan 208, according to an embodiment of the present disclosure. The fan 208 includes a hub 402 configured to rotate about an axis. Particularly, the hub 402 is coupled to a shaft 404 (shown in FIG. 2 and FIG. 3) of the motor 206 and configured to rotate about the longitudinal axis “L” of the cabinet 202. The fan 208 further includes a plurality of fan blades 406-1, 406-2, 406-3 (hereinafter collectively and individually referred to as “the fan blade 406”) coupled to the hub 402 and located circumferentially along periphery of the hub 402. Preferably, each fan blade 406 is located radially equidistant from an adjacent fan blade 406. Each fan blade 406 extends between a root 408 and a tip edge 410 thereof and defines a leading edge 412 and a trailing edge 414.

FIG. 4B illustrates a front view of one of the fan blades 406 of the fan 208 of FIG. 4A. The root 408 of the fan blade 406 is connected to the hub 402 via an arm 416. In an embodiment, the fan blade 406 includes a first portion 418 extending radially from the arm 416 and inclined at a first predefined angle (θ) with respect to the hub 402. In an embodiment, the first portion 418 of the fan blade 406 is non-planar. As such, a chord “C1” considered in the first portion 418 and extending between the trailing edge 414 and the leading edge 412 defines the first predefined angle (θ) with respect to a horizontal extending along surface of the hub 402 as shown in FIG. 4B. In an embodiment, the first predefined angle (θ) may be in a range of about 20 degrees to about 30 degrees. In another embodiment, the first predefined angle may be in a range of about 22 degrees to about 27 degrees. In yet another embodiment, the first predefined angle may be about 23.8 degrees. The first portion 418 is configured to induce an axial flow of air (indicated by an arrow “AX” in FIG. 4A and FIG. 4B). As used herein, the term “axial flow” may refer to flow of air induced by the fan 208 along the longitudinal axis “L” of the cabinet 202 in a direction outward with respect to the cabinet 202.

FIG. 4C illustrates a perspective view of one of the fan blades 406 of the fan 208 of FIG. 4A. The fan blade 406 also includes a second portion 420 embodied as a non-planar portion. The second portion 420 extends from the first portion 418 and between the leading edge 412 and the trailing edge 414 of the fan blade 406.

In some embodiments, a span “S2” of the second portion 420 may be less than a span “S1” of the first portion 418 of the fan blade 406. In some embodiments, length of a chord “C2” in the second portion 420 may be equal to the length of the chord “C1” in the first portion 418. In some embodiments, length of the chord “C2” in the second portion 420 may be less than the length of the chord “C1” in the first portion 418. The second portion 420 is configured as an airfoil to define an angle of attack (α), with respect to the air flowing across the second portion 420, and to induce a radial inward flow of air (indicated by arrow “R” in FIG. 4A and FIG. 4C) towards the hub 402 of the fan blade 406. The phrase “angle of attack” refers to an angle defined between the chord in the airfoil and the direction of the air flowing across the second portion 420. Generally, the direction of air flowing across the second portion 420 is substantially perpendicular to a radial direction of the fan blade 406. In an embodiment, the induced radial inward flow of air is in a range of about 3.5% to about 12.5% of the induced axial flow of air. In another embodiment, the induced radial inward flow of air is in a range of, but not limited to, about 5% to about 10% of the induced axial flow of air. In yet another embodiment, the induced radial inward flow of air is in a range of about 6% to about 9% of the induced axial flow of air. In some embodiments, the fan blade 406 may be made of one of, but not limited to, plastic, metal, and composite material.

According to an aspect of the present disclosure, a radius of curvature of a trailing edge segment 422 of the second portion 420 is less than a radius of curvature of a leading edge segment 424 of the second portion 420. The radius of curvature of the trailing edge segment 422 creates a cambered airfoil profile that is associated with the angle of attack (α), such that the second portion 420 of the fan blade 406 induces the radial inward flow of air. In an embodiment, the leading edge segment 424 of the second portion 420 is bent inward towards the hub 402 to define the angle of attack (α) with respect to the air flowing across the leading edge segment 424 of the second portion 420.

In an embodiment, the angle of attack (α) of the fan blade 406 is in a range of zero degrees to about 10 degrees, and preferably in a range of about 3 degrees to about 10 degrees. In another embodiment, the angle of attack (α) may be in a range of about 5 degrees to about 8 degrees. In yet another embodiment, the angle of attack (α) may be in a range of about 6 degrees to about 7.5 degrees. In some embodiments, the angle of attack (α) may be predefined based on, but not limited to, a desired amount of radial flow of air, diameter of the fan 208, desired rotation speed of the fan 208, the length of the chord “C2” in the second portion 420 of the fan blade 406, and the span “S2” of the second portion 420 of the fan blade 406.

In an embodiment, a portion of the leading edge segment 424 of the second portion 420 extends perpendicular with respect to the first portion 418. Additionally, in some embodiments, a portion of the trailing edge segment 422 of the second portion 420 may extend perpendicular with respect to the first portion 418. In an embodiment, a distance between the trailing edge segment 418 of the second portion 420 and a center of the hub 402 may be less than a distance between the leading edge segment 424 of the second portion 420 and the center of the hub 402.

As can be seen in FIG. 4C, the second portion 420 blends with the first portion 418. In an embodiment, due to a gradual increase in the radius of curvature from the trailing edge 414 to the leading edge 412, the angle of attack (α) at the tip edge 410 of the fan blade 406 may be lower than the angle of attack (α) at a base 426 of the second portion 420, with respect to the radial direction of the fan blade 406. In other words, the angle of attack (α) gradually reduces from the base 426 towards the tip edge 410 of the fan blade 406. As such, the second portion 420 of the fan blade 406 may be associated with varying angles of attack. As used herein, the term “base” refers to the region where the first portion 418 meets the second portion 420.

In some embodiments, the tip edge 410 may be uncambered and may be associated with zero degree angle of attack. In alternate embodiments, the fan blade 406 may be designed to define lesser length of chord at the tip edge 410 when compared to lengths of chords downstream along the span “S2” of the second portion 420. Such design of the fan blade 406 may help reduce inward lift of air at the tip edge 410 and reduce losses at the tip edge 410, thereby enhancing efficiency of the fan blade 406. In some embodiments, the tip edge 410 may be parallel to the hub 402. Additionally, in some embodiments, a width “W1” of the tip edge 410 may be less than a width “W2” of the first portion 418 of the fan blade 406. As such, the fan blade 406 may have a trapezoidal shape along the span thereof.

During operation of the fan 208, the air present in the cabinet 202 and flowing across the first portion 418 of the fan blade 406 is guided along the longitudinal axis “L” of the cabinet 202 in a direction outward with respect to the cabinet 202. Further, the air flowing across the second portion 420 is guided in the radial direction of the fan blade 406 and subsequently guided outward, along with the axially flowing air, in the direction outward with respect to the cabinet 202. In such arrangement, a lift generated by the airfoil profile of the second portion 420 may be based on at least one of, but not limited to, shape of the second portion 420, the angle of attack with respect to the air flowing across the second portion 420, the length of the chord “C2” in the second portion 420, velocity of the air flowing across the second portion 420, and density of the air flowing across the second portion 420. In some embodiments, a desired lift (radial inward flow of the air) may be achieved by a combination of varied angles of attack and the length of the chord “S2” in the second portion 420 of the fan blade 406. In some embodiments, the desired lift may be achieved solely by varying the length of the chord “C2” in the second portion 420 of the fan blade 406. According to an aspect, vortex bound to the airfoil profile of the second portion 420 is guided towards the tip end 410 of the fan blade 406 to allow shedding of the vortex. As such, the second portion 420 allows in reduction of vortices in horizontal plane, thereby reducing induced drag and axial thrust of the fan 208. Additionally, the gradual reduction in the angle of attack towards the tip edge 410 reduces intensity of vortices.

FIG. 5A illustrates a fan blade 500 according to another embodiment of the present disclosure. Ends of trailing edge 502 and leading edge 504 of the fan blade 500, distant from a hub 506, may be rounded as shown in FIG. 5A.

FIG. 5B illustrates a fan blade 550 according to yet another embodiment of the present disclosure. The length of the chord “C2” in the second portion 420 of the fan blade 420 may be reduced to arrive at a configuration of the fan blade 550. In this embodiment, a tip edge 552 of the fan blade 550 is arcuate, such that a chord considered along the tip edge 552 is inclined towards a leading segment 554 of the fan blade 550, thereby rendering a shortened length of the leading segment 554 as shown in FIG. 5B.

FIG. 6 shows a velocity profile 600 of air flowing across the cabinet 202 of FIG. 3, according to an aspect of the present disclosure. As can be seen in FIG. 6, owing to configuration of the fan blade 406, an upper half of the height “H” of the cabinet 202, particularly the upper portion 304 of the cabinet 202, receives uniform flow of air associated with a velocity of about 220 ft/min as against minimum or no flow of air in corresponding upper portion of conventional cabinets of outdoor units. Particularly, about 30% to about 50% increase in the velocity of air flowing across the upper portion 304 of the cabinet 202 may be achieved with respect to the conventional cabinets of outdoor units. Therefore, the fan 208 of the present disclosure eliminates maldistribution of flow of air across the cabinet 202. As such, the refrigerant tubes 212 located at the upper portion 304 of the cabinet 202 are allowed to exchange heat with the air flowing across the upper portion 304 of the cabinet 202, thereby enhancing the efficiency of the AC system 100.

Further, the second portion 420 of the fan blade 406 is partially concealed by the bell mouth 302 in the transverse direction of the cabinet 202. In some embodiments, the span “S2” of the second portion 420 may be designed to reduce length of the bell mouth 302 or eliminate requirement of the bell mouth 302, thereby allowing reduction in cost of manufacturing the cabinet 202 besides achieving the uniform flow of air in the upper portion 304 of the cabinet 202. In some embodiments, the motor 206 may be associated with higher RPM and the second portion 420 of the fan blade 406 may be associated with lesser angle of attack to achieve the uniform flow of air across the cabinet 202.

FIG. 7A illustrates another fan 700 and FIG. 7B illustrates a fan blade 702 of the fan 700, according to an embodiment of the present disclosure. Each of the plurality of fan blades 702 may be embodied as a swept blade including a first portion 704 and a second portion 706. Similar to the embodiments described earlier, the second portion 706 extends from the first portion 704 and is configured to induce a radial flow of air towards a hub 708 of the fan 700. In an embodiment, the second portion 706 extends arcuately from the first portion 704 as shown in FIG. 7B.

To this end, it will be understood that the fan blade 406 of the present disclosure, particularly the second portion 420 of the fan blade 406, improves the flow of air in the upper portion 304 of the cabinet 202, thereby reducing or eliminating airflow maldistribution which was otherwise caused due to layout of conventional cabinets including motor, axial fan, and venturi. Due to such uniform flow of air in the upper portion 304 of the cabinet 202, the refrigerant flowing through the refrigerant tubes 212 routed through the upper portion 304 is allowed to exchange heat with the air flowing across the refrigerant tubes 212, thereby enhancing heat exchange efficiency of the outdoor unit 106 and overall efficiency of the AC system 100. In an implementation, the fan 208 of the present disclosure may be deployed in a horizontally oriented outdoor unit of a split type air conditioning system.

While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof. 

What is claimed is:
 1. A fan comprising: a hub configured to rotate about an axis; a plurality of fan blades coupled to the hub and located circumferentially along the hub, wherein each fan blade extends between a root and a tip edge, the fan blade comprising: a first portion inclined at a first predefined angle with respect to the hub, the first portion configured to induce an axial flow of air; and a second portion extending from the first portion and between a leading edge and a trailing edge of the fan blade, the second portion configured as an airfoil defining an angle of attack to induce a radial inward flow of air, wherein a radius of curvature of a trailing edge segment of the second portion is less than a radius of curvature of a leading edge segment of the second portion.
 2. The fan of claim 1, wherein a portion of the leading edge segment of the second portion extends perpendicular with respect to the first portion of the fan blade.
 3. The fan of claim 1, wherein the leading edge segment of the second portion is bent inward towards the hub to define the angle of attack of the fan blade.
 4. The fan of claim 3, wherein a distance between the trailing edge segment of the second portion and a center of the hub is less than a distance between the leading edge segment of the second portion and the center of the hub.
 5. The fan of claim 3, wherein the angle of attack at the tip edge of the fan blade is lower than the angle of attack at a base of the second portion, with respect to a radial direction of the fan blade.
 6. The fan of claim 3, wherein the angle of attack of the fan blade is in a range of about 3 degrees to about 15 degrees.
 7. The fan of claim 1, wherein a span of the second portion is less than a span of the first portion of the fan blade.
 8. The fan of claim 1, wherein the induced radial inward flow of air is in a range of about 5% to about 10% of the induced axial flow of air.
 9. The fan of claim 1, wherein the first portion of the fan blade in non-planar.
 10. The fan of claim 1, wherein each of the plurality of fan blades is made of one of plastic, metal, and composite material.
 11. The fan of claim 1, wherein each of the plurality of fan blades is a swept blade.
 12. An air handling unit comprising: a cabinet; a motor housed within the cabinet; and a fan operably coupled to the motor, the fan configured to allow a uniform inflow of air at an upper portion of the cabinet and direct the air from inside of the cabinet to outside of the cabinet, the fan comprising: a hub coupled to a shaft of the motor and configured to rotate about an axis; and a plurality of fan blades coupled to the hub and located circumferentially along the hub, wherein each fan blade extends between a root and a tip edge, the fan blade comprising: a first portion inclined at a first predefined angle with respect to the hub, the first portion configured to induce an axial flow of air; and a second portion extending from the first portion and between a leading edge and a trailing edge of the fan blade, the second portion configured as an airfoil defining an angle of attack to induce a radial inward flow of air, wherein a radius of curvature of a trailing edge segment of the second portion is less than a radius of curvature of a leading edge segment of the second portion.
 13. The air handling unit of claim 12 further comprising a plurality of refrigerant tubes extending along a periphery of the cabinet, wherein the fan is configured to induce airflow over the plurality of refrigerant tubes to achieve heat exchange with respect to the plurality of refrigerant tubes.
 14. The air handling unit of claim 12, wherein the induced radial inward flow of air is in a range of about 5% to about 10% of the induced axial flow of air.
 15. The air handling unit of claim 12, wherein a portion of the leading edge segment of the second portion of the fan blade extends perpendicular with respect to the first portion of the fan blade.
 16. The air handling unit of claim 12, wherein the leading edge segment of the second portion of the fan blade is bent inward towards the hub to define the angle of attack of the fan blade.
 17. An air handling unit comprising: a cabinet; a motor housed within the cabinet; a bell mouth extending from the cabinet in a direction inward along a longitudinal axis of the cabinet, the bell mouth configured to partially conceal the motor in a transverse direction of the cabinet; and a fan operably coupled to the motor, the fan configured to allow a uniform inflow of air at an upper portion of the cabinet and direct the air from inside of the cabinet to outside of the cabinet through the bell mouth, the fan comprising: a hub coupled to a shaft of the motor and configured to rotate about the longitudinal axis of the cabinet; and a plurality of fan blades coupled to the hub and located circumferentially along the hub, wherein each fan blade extends between a root and a tip edge, the fan blade comprising: a first portion inclined at a first predefined angle with respect to the hub, the first portion configured to induce an axial flow of air; and a second portion extending from the first portion and between a leading edge and a trailing edge of the fan blade, the second portion configured as an airfoil defining an angle of attack to induce a radial inward flow of air, wherein the second portion is partially concealed by the bell mouth in the transverse direction of the cabinet, and wherein a radius of curvature of a trailing edge segment of the second portion is less than a radius of curvature of a leading edge segment of the second portion.
 18. The air handling unit of claim 17, wherein the induced radial inward flow of air is in a range of about 5% to about 10% of the induced axial flow of air.
 19. The air handling unit of claim 17 further comprising a plurality of refrigerant tubes extending along a periphery of the cabinet, wherein the fan is configured to induce airflow over the plurality of refrigerant tubes to achieve heat exchange with respect to the plurality of refrigerant tubes.
 20. The air handling unit of claim 17 further comprising a fan guard coupled to an outlet of the bell mouth. 